Spirit, the NASA rover that has trundled across the Mars landscape since 2004, will no longer rove. If it survives a hibernation through the fierce cold of the oncoming winter, it will continue operations as a science station, NASA announced in a telecon on Tuesday. Spirit has been trapped in a bed of sand since last May, and engineers have been unable to free it.

Principal investigator Steve Squyres of Cornell University said Spirit could still perform science without moving — and in fact, staying still made some science tasks easier. If it emerges from a 45 degree Celsius freeze this spring (Mars’ winter solstice is in May), Spirit will watch for consistent weather patterns and examine the soil in which it’s stuck – sulfate rich stuff that may have formed billions of years ago in steaming vents. But Squyres was most excited about a chance to do something that had been attempted by three previous landers, the twin Vikings and the short-lived Pathfinder mission. By listening to the rover’s radio signals, scientists can measure the orbit and spin of Mars, which in turn can lead to an estimate of Mars’ subtle wobble. With this, Squyres hopes to deduce whether Mars has a liquid or solid iron core.

Spirit’s sister rover, Opportunity, marches on; the cost to operate both missions is $20 million a year. Mars Exploration Program Chief Doug McCuistion couldn’t say how much cheaper operating Spirit as a station would be.